Not to be confused with Scenester (largely involved with emo, hardcore, and post-hardcore) or Indie-Rocker (self-explanatory), hipsters are normally thin middle class 18-25 year olds who listen various styles of independent music, which is rarely rock oriented (though nu-grunge, nu-psych, and metal are making a comeback).
The female fashion ranges from largely thrifted vintage looking clothing to elaborately designed obscure fashion designers (Dries, Anne D, etc.); the men often use similar styles, wearing tapered jeans most of which are black (though sagged dropped crotch jeans are the new thing), oversized shirts (opposite of the misnomer that extremely tight t-shirts are hipster, as they are definitively scenester), dress shoes or high top sneakers and large rimmed glasses.
Politically hipsters are generally apathetic, but recently as the hipster bible Vice has shifted politically from the right to the left, the hipster mass has followed. The rise of 90s revival culture has also brought back the use of marijuana and X and has replaced cocaine, though the ever popular PBR and American Spirit Cigarettes remain popular.
Overall, hipsters can be characterized by their relatively carefree and iconoclastic lifestyles, their adherence to debauchery and sexual freedom, and the intake of drugs and alcohol.
I went to the juke club and to my surprise, the place was filled with hipsters.